The PDCA cycle in ISO 9001 requirements

Archived article: the clause numbers below follow the ISO 9001:2008 structure. They are retained to illustrate PDCA and must not be used as clause references for later editions.

The improvement cycle is associated with Dr Walter Shewhart, a pioneer of quality management. Dr W. Edwards Deming commonly used PDSA (plan–do–study–act), emphasising learning from analysis rather than simply checking results. Organisations often concentrate on planning and doing while giving less attention to checking and acting. An effective ISO 9001 quality management system needs a balanced approach to all four stages.

This article examines PDCA through ISO 9001 requirements. Using the earlier clause structure discussed here, planning appears throughout the standard, Clause 7 focuses on product realisation, and Clause 8 addresses measurement, analysis and improvement. Which activities tend to receive too little attention?

Checking and acting can be harder to sustain than planning and implementation. To apply ISO 9001 effectively, organisations need to make time for reviewing results and acting on findings. The following sections relate the PDCA stages to the clause structure used in the original article.

1. Plan

An annual business plan may cover the organisation's vision and mission, quality policy, performance objectives, budgets, maintenance, standards, key milestones, and new products, markets or processes. The original article groups planning-related requirements into the following seven areas.

• Maintaining the quality management system (4.1).
• Quality management system documentation (4.2).
• Management responsibility (5).
• Resource management (6).
• Planning product realisation (7.1).
• Control of monitoring and measuring equipment (7.6).
• Preventive action (8.5.3).

Most of these are readily recognised as planning activities. Preventive action (8.5.3) appears under measurement, analysis and improvement, yet it involves planning to eliminate potential failures before they occur. If a failure does not occur, it may be difficult to establish whether prevention caused that outcome. The article therefore treats preventive action as intentional planning, even though its implementation also involves action.

2. Do

Implementation occurs more frequently, for example through monthly operating cycles, and generates the data used to measure and analyse delivery of the annual plan. In the earlier structure, much of this work falls within Clause 7, Product realisation, where many operational records are created.

• Competence and training (6.2.2).
• Design and development (7.3).
• Purchasing (7.4).
• Production and service provision (7.5).

3. Check

Once implementation produces data, analyse and study it. Checking should go beyond confirming that activities are complete or that data exists: turn the data into information that explains performance and supports decisions.

ISO 9001 identifies review, measurement and analysis processes that help organisations assess progress against their plans.

• Management review (5.6).
• Monitoring and measurement (8.2).
• Customer satisfaction (8.2.1).
• Internal audit (8.2.2).
• Data analysis (8.4).

These are not one-off events. Ongoing checks produce trends that help convert data into useful management information.

Monthly or quarterly reviews can be practical. Some organisations rely mainly on an annual audit, management review or customer survey, but review frequency should reflect operating conditions, change and risk. A highly stable market with little competition is unusual; organisations need a review rhythm that allows them to respond to actual performance.

4. Act

Act promptly on gaps identified by comparing plans with performance data. Management review also contains an action stage: after reviewing the necessary inputs, assign responsibility for the corrective and, in the earlier standard's terminology, preventive actions that are needed.

Actions include controlling nonconforming products and implementing corrective action, with preventive action addressing potential nonconformities in the earlier clause structure.

• Nonconforming product (8.3).
• Corrective action (8.5.2).
• Preventive action (8.5.3).

Connected PDCA cycles across the system

An ISO 9001 QMS contains many connected PDCA cycles. Product realisation itself involves planning requirements, carrying out design and development, reviewing results and changing the design where needed. Similar cycles apply to training, document control, purchasing, auditing and corrective action. These linked cycles support continual improvement across the system.

Reference document: ISO 9001:2015